The present invention relates to a sensor mounting structure for mounting an automotive sensor (e.g., a pressure sensor, a temperature sensor, etc.) and a semiconductor pressure sensor to be used.
There have been used various kinds of sensors for electronically controlling an internal-combustion engine mounted in a motor vehicle. These conventional sensors were attached by screws. For instance, as disclosed in Japanese Unexamined Patent Publication No. Hei 5-172673, brackets are attached in two places on a plastic molding housing to provide the pressure sensor mounting position with a degree of freedom of movement. The pressure sensor is attached by screws in an appropriate position through the bracket and the sensor section and a pressure source are connected by means of a hose.
In recent years, a metal intake air passage, or a so-called intake manifold made of a metal, for use in the internal-combustion engine in motor vehicles is giving way to an intake manifold of synthetic resin. In the case of the synthetic resin manifold, it becomes necessary to form, by insert-molding, a metal part for receiving a mounting screw to fix a sensor housing at the time of molding the intake manifold, resulting in an increased cost.
It is also necessary to insert a metal bushing on the housing side to prevent biting and loosening of the screw, which also increases the cost.
To facilitate the mounting of the sensor, therefore, there has been proposed a method of dispensing with a bracket and a hose for introducing the pressure from the pressure source, and fixing the sensor directly on the pipe wall of the intake air passage in place of using the screw.
For instance, according to Japanese Unexamined Patent Publication No. Sho 63-215847, a cylindrical section larger in diameter than the sensor body is employed as the sensor mounting section. On the sensor side is provided a locking flange section of a non-circular contour; and an insertion hole is formed in the cylindrical section to insert the sensor. The insertion hole has a locking hole for inserting the locking flange portion of the sensor at a specific angle in the inlet side and, after insertion, the locking flange section is allowed to turn. The locking flange section of the sensor is locked by a spring force on the inside surface of the locking hole to thereby mount the sensor.
This method, however, requires insertion of a spring member beside the sensor body into the sensor mounting section (cylindrical section), which will increase both cost and labor for assembling.
In Japanese Unexamined Patent Publication No. Sho 63-215846, disclosed is the sensor mounting structure that a cylindrical portion is provided as a sensor mounting section which is larger than the sensor body; on either one of the cylindrical portion and the sensor, there is provided an elastic locking leg which is elastically deformable in the radial direction of the cylindrical portion; on the other, a fixed locking portion is provided to lock and lock the sensor from turning in engagement with the elastic locking leg in a free state; and the elastic locking leg is pressed into contact with the fixed locking portion by the force of a disk spring, to thereby prevent accidental removal of the sensor. In this case also, it becomes necessary to form a cylindrical portion as the sensor mounting section, and to insert a spring member beside the sensor body into the sensor mounting section (cylindrical portion), resulting in an increased cost and labor for assembling.
In Japanese Unexamined Patent Publication No. Hei 10-122914 there has been proposed a sensor mounting structure in which an elastic member (e.g., a rubber member) having a front end flange and a rear end flange is attached on the projecting portion of a sensor; the elastic member together with the projecting portion of the sensor is inserted, with the rear end flange left non-inserted, into a through hole provided in a member to be attached. After insertion, the front end flange is locked on the inside surface of the member to be attached, while the rear end flange is locked on the outside surface of the member to be attached. The example given above requires an elastic member for mounting the sensor, which increases the number of component parts, and furthermore requires a process for mounting the elastic member to the projecting portion of the sensor prior to mounting the sensor.
It is, therefore, an object of the present invention first to provide a sensor mounting structure for motor vehicles which facilitates mounting the sensor to the wall of the intake manifold while dispensing with screwing of the sensor, and further to decrease the number of component parts and to simplify the structure as compared with a conventional mounting structure system which needs no screws.
It is another object to provide a semiconductor pressure sensor capable of directly mounting an intake air pressure sensor which is one of automotive sensors, to the wall of the intake manifold, and installing the pressure detecting gauge of the sensor into the intake passage while dispensing with a pressure inlet pipe.
It is further another object to provide a sensor mounting structure capable of preventing water formed by condensation from icing in the pressure detecting section to maintain reliability of the pressure detecting section when the semiconductor pressure sensor is mounted directly on the wall of the intake manifold, particularly when the semiconductor pressure sensor is mounted with the pressure inlet port in a horizontal or nearly horizontal position.